<html><head><style> body {height: 100%; color:#000000; font-size:12pt; font-family:arial, helvetica, sans-serif;}</style></head><body><div>Dear George,<br></div><div>Good work. Let me ponder on this a bit. I am sure our colleaguyes<br></div><div>will send their thoughts. Have a good weekend.<br></div>-H<div><br></div><div>----- Original Message -----<br>From: George Kharashvili <georgek@jlab.org><br>To: isotope-prod@jlab.org<br>Sent: Fri, 08 Jan 2016 17:10:40 -0500 (EST)<br>Subject: [Isotope-prod] Comments on Ga activation rates<br></div><div><br></div><div>Dear collaboration members,<br></div><div><br></div><div>I did some modeling to include activation rates of various targets mentioned yesterday. Here are some conclusions:<br>- There is no good reason to increase radiator thickness - 1 to 1.5 mm tungsten is optimal.<br>- Activation rates presented in the proposal (17 mCi/h/kW at 40 MeV) were calculated for what can be assumed an infinite natural Ga target. Replacing it with other targets results in the following:<br>3cm diameter, 5 cm long cylinder (m=210g) - 10 mCi/h/50kW<br>3cm diameter, 10 cm long cylinder (m=420g) - 12 mCi/h/50kW<br>Truncated cone D1=1.5cm D2=10.6cm H=6.5cm (m=1310g) (currently in the proposal) - 13 mCi/h/50kW<br>Truncated cone D1=2cm D2=6cm H=10cm (m=800g) - 12 mCi/h/50kW<br>Truncated cone D1=1.5cm D2=15.5cm H=10cm (m=4110g) - 15 mCi/h/50kW<br></div><div><br></div><div>If we take the smallest of these targets (~200g) and assume 20 hours of 50 kW beam (ignoring decay of Cu-67), we should produce ~200 mCi of Cu-67. This is roughly 260 nanograms, or 1.3 ppb of Cu-67 in our 200 g natural Ga target, which is greater than the 0.5 ppb of Cu content of 99.9999% Ga sample.<br></div><div><br></div><div>I hope this information is useful for the proposal.<br></div><div><br></div><div>--<br>George Kharashvili<br>Jefferson Lab Radiation Control<br>757-269-6435<br>_______________________________________________<br>Isotope-prod mailing list<br>Isotope-prod@jlab.org<br>https://mailman.jlab.org/mailman/listinfo/isotope-prod<br></div><div><br></div></body></html>